Sculpting a photorealistic human face for animation: use the multiresolution modifier?
From what I understand about the development of blender and the workflows that are out there, the multi resolution modifier is no longer frequently used, and for good reason. I think it still has uses, but overall it's no longer an essential modifier for workflows such as the one you describe. 

The multiresolution modifier was, for a long time, the only feasible way to sculpt in Blender. Manually creating a dense mesh or using the subsurf modifier (applied) was an option, but these are destructive methods that lead to objects that are so dense they are difficult to edit.

With the addition of dynamic topology, there is now a way for an artist to create highly detailed objects without this modifier. In your case, a scanned object replaces this, but the  results are the same: You and up with a dense triangulated mesh, and the workflow you outlined is a great way of turning that into a final product.

Since dynamic topology is much more free from an artistic point of view than the multires modifier (you don't have to worry about topology at all) it's no longer used much for initial sculpts as there are better options out there.

However, the multiresolution modifier still has a place, and that place is in  adding details to modeled meshes. Not everyone is a sculptor, and sometimes hand modeling an object is the best way to go about it. If you then want to add details, this is where the mutiresolution modifier is great. It allows the artist to add details non destructively, and gives the option of baking this detail to maps. Using an applied subsurf modifier or a dense mesh won't allow you to do this, as any detail you add is practically permanent.

Finally, the mutiresolution modifier can still be a good way to sculpt an object from scratch, provided the topology is OK, or you start with a simple model. All in all, this modifier has it's uses, mainly in workflows where a mesh with good topology is the starting point.